Transmission Line Coupler for Testing of Integrated Circuits

ABSTRACT

The present disclosure describes a semiconductor wafer testing environment for routing signals used for testing integrated circuits formed onto a semiconductor wafer. The semiconductor wafer testing environment includes a semiconductor wafer tester to control overall operation and/or configuration of the semiconductor wafer testing environment and a semiconductor wafer prober to test the integrated circuits formed onto the semiconductor wafer. The semiconductor wafer prober includes a probe card having a transmission line coupler formed onto a flexible substrate. The transmission line coupler includes multiple transmission line coupling blocks that extend radially from a central point of the flexible substrate in a circular manner.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentAppl. No. 62/278,250, filed Jan. 13, 2016, which is incorporated hereinby reference in its entirety.

BACKGROUND

Field of Disclosure

The present disclosure relates generally to semiconductor wafer testing,and including a transmission line coupler for routing of signals duringthe semiconductor wafer testing.

Related Art

A semiconductor device fabrication operation is commonly used tomanufacture components onto a semiconductor substrate to form asemiconductor wafer. The semiconductor device fabrication operation usesa predetermined sequence of photographic and/or chemical processingsteps to form components onto the semiconductor substrate. However,imperfections within the semiconductor wafer, such as imperfections ofthe semiconductor substrate, imperfections of the semiconductor devicefabrication operation, or imperfections in design of the componentsthemselves, may cause one or more of the semiconductor components tooperate differently than expected.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

Embodiments of the disclosure are described with reference to theaccompanying drawings. In the drawings, like reference numbers indicateidentical or functionally similar elements. Additionally, the left mostdigit(s) of a reference number identifies the drawing in which thereference number first appears. In the accompanying drawings:

FIG. 1 illustrates a semiconductor wafer testing environment accordingto an exemplary embodiment of the present disclosure;

FIG. 2 schematically illustrates a transmission line coupler that can beimplemented within a probe card of the semiconductor wafer testingenvironment according to an exemplary embodiment of the presentdisclosure;

FIGS. 3A and 3B illustrate mechanical layouts of the transmission linecoupler according to exemplary embodiments of the present disclosure;

FIG. 4 further illustrates the mechanical layout of the transmissionline coupler according to an exemplary embodiment of the presentdisclosure;

FIG. 5 illustrates a mechanical layout of a transmission line couplingblock of the transmission line coupler according to an exemplaryembodiment of the present disclosure; and

FIG. 6 illustrates a mechanical layout of a transmission line coupler ofthe transmission line coupling block according to an exemplaryembodiment of the present disclosure.

The disclosure will now be described with reference to the accompanyingdrawings. In the drawings, like reference numbers generally indicateidentical, functionally similar, and/or structurally similar elements.The drawing in which an element first appears is indicated by theleftmost digit(s) in the reference number.

DETAILED DESCRIPTION OF THE DISCLOSURE

Overview

The present disclosure describes a semiconductor wafer testingenvironment for routing signals used for testing integrated circuitsformed onto a semiconductor wafer. The semiconductor wafer testingenvironment includes a semiconductor wafer tester to control overalloperation and/or configuration of the semiconductor wafer testingenvironment and a semiconductor wafer prober to test the integratedcircuits formed onto the semiconductor wafer. The semiconductor waferprober includes a probe card having a transmission line coupler formedonto a flexible substrate. The transmission line coupler includesmultiple transmission line coupling blocks that extend radially from acentral point of the flexible substrate in a circular manner.

Exemplary Semiconductor Wafer Testing Environment

FIG. 1 illustrates a semiconductor wafer testing environment accordingto an exemplary embodiment of the present disclosure. A semiconductordevice fabrication operation is commonly used to manufacture integratedcircuits 102.1 through 102.n onto a semiconductor substrate 104 to forma semiconductor wafer 106. The semiconductor device fabricationoperation uses a predetermined sequence of photographic and/or chemicalprocessing steps to form the integrated circuits 102.1 through 102.nonto the semiconductor substrate 104. In some situations, imperfectionswithin the semiconductor wafer 106, such as imperfections of thesemiconductor substrate 104, imperfections of the semiconductor devicefabrication operation, or imperfections in design of the integratedcircuits 102.1 through 102.n themselves to provide some examples, maycause one or more of the integrated circuits 102.1 through 102.n tooperate differently than expected. A semiconductor wafer testingenvironment 100 allows for testing of the semiconductor wafer 106 toverify that the integrated circuits 102.1 through 102.n operate asexpected. The semiconductor wafer testing environment 100 includes asemiconductor wafer tester 108 and a semiconductor wafer prober 110.

The semiconductor wafer tester 108 controls overall operation and/orconfiguration of the semiconductor wafer testing environment 100. Thesemiconductor wafer tester 108 includes one or more source instrumentsto provide one or more testing signals 150 to the semiconductor waferprober 110 and/or one or more capture instruments to analyze one or moretesting signals 152 received from the semiconductor wafer prober 110.During operation, the semiconductor wafer tester 108 executes one ormore testing routines to verify operation of the integrated circuits102.1 through 102.n. The one or more testing routines include one ormore instructions that are executable by the semiconductor wafer tester108 to verify that the integrated circuits 102.1 through 102.n operateas expected. A first instruction from among the one or moreinstructions, when executed by the semiconductor wafer tester 108,causes the one or more source instruments to provide the one or moretesting signals 150. A second instruction from among the one or moreinstructions, when executed by the semiconductor wafer tester 108,causes the one or more capture instruments to analyze the one or moretesting signals 152 received from the semiconductor wafer prober 110.The testing signals 150 and/or the testing signals 152 can includevarious optical signals, various electrical signals, such as one or moreanalog signals and/or one or more digital signals to provide someexamples, and/or various other signals that will be readily apparent tothose skilled in the relevant art(s) without departing from the spiritand scope of the present disclosure. In an exemplary embodiment, the oneor more analog signals can include radio frequency (RF) signals that arecharacterized as having a frequency of approximately 60 Gigahertz (GHz).

The semiconductor wafer prober 110 tests the integrated circuits 102.1through 102.n. During operation, the semiconductor wafer prober 110loads and unloads the semiconductor wafer 106 for testing. Once thesemiconductor wafer 106 has been loaded within the semiconductor waferprober 110, the semiconductor wafer prober 110 aligns one or moremechanical probes of a probe card 112 with one or more contact pads onthe semiconductor wafer 106. In an exemplary embodiment, thesemiconductor wafer prober 110 can include automatic pattern recognitionoptics to align the semiconductor wafer 106 with sufficient accuracy toensure accurate registration between the one or more contact pads on thesemiconductor wafer 106 and the one or more mechanical probes of theprobe card 112. After the one or more mechanical probes have beenaligned with the one or more contact pads on the semiconductor wafer106, the semiconductor wafer prober 110 provides the testing signals 150from the semiconductor wafer tester 108 to the probe card 112 and/orreceives the testing signals 152 from the probe card 112.

As illustrated in FIG. 1, the probe card 112 includes a flexibletransmission line coupler 114 mechanically mounted and electricallyconnected to a printed circuit board (PCB) 116. The PCB 116 routesvarious signals between the semiconductor wafer 106 and semiconductorwafer prober 110, such as testing signals 150, testing signals 152,testing signals 154, and/or testing signals 156 to provide someexamples. In an exemplary embodiment, the PCB 116 can include one ormore surface mount connectors to electrically connect to variouscommunication cables that are used for routing the testing signals 152and/or testing signals 150. Although not illustrated in FIG. 1, the PCB116 includes a mechanical recess beneath the flexible transmission linecoupler 114. The one or more mechanical probes of the probe card 112 arepositioned within this mechanical recess. The one or more mechanicalprobes provide electrical connectivity between the semiconductor wafer106 and the probe card 112 when sufficiently aligned. The one or moremechanical probes receive testing signals 154 from the semiconductorwafer 106 and/or provide the testing signals 156 to the semiconductorwafer 106. In an exemplary embodiment, the one or more mechanical probesattach directly to the flexible transmission line coupler 114, which inturn connects electrically and mechanically to the PCB 116. However, inanother exemplary embodiment, the mechanical probes may connect directlyto the PCB 116, and the transmission line coupler 114 may connect to thePCB 116 separately.

The flexible transmission line coupler 114 includes transmission linecouplers 118.1 through 118.m. formed onto a flexible substrate 120, toroute the testing signals 150 to the semiconductor wafer 106 as thetesting signals 156 and/or to route the testing signals 154 from thesemiconductor wafer 106 as the testing signals 152.

Exemplary Electrical Schematic of a Transmission Line Coupler that canbe Implemented with a Probe Card of the Semiconductor Wafer TestingEnvironment

FIG. 2 schematically illustrates a transmission line coupler that can beimplemented within a probe card of the semiconductor wafer testingenvironment according to an exemplary embodiment of the presentdisclosure. Although the discussion of the transmission line coupler tofollow is described in terms of the semiconductor wafer testingenvironment, this is for illustrative purposes only. Those skilled inthe relevant art(s) will recognize that the transmission line couplercan be used in other environments without departing from the spirit andscope of the present disclosure. For example, the transmission linecoupler can be implemented on a generic PCB as part of a transmitter,receiver, or transceiver within a communications environment.

As discussed above, the transmission line couplers 118.1 through 118.mroute the testing signals 150, the testing signals 152, the testingsignals 154, and/or the testing signals 156 between the semiconductorwafer tester 108 and the integrated circuits 102.1 through 102.n by wayof the one or more mechanical probes. A transmission line couplingcircuit 200 represents an exemplary embodiment of one or more of thetransmission line couplers 118.1 through 118.m. The transmission linecoupling circuit 200 includes transmission line coupling blocks 202.1through 202.a. In an exemplary embodiment, the transmission linecoupling blocks 202.1 through 202.a include transmission line couplingblocks 202.1 through 202.9 that are configured to route various signalsat frequencies in the GHz range, such as approximately 60 GHz to providean example. The transmission line coupling blocks 202.1 through 202.ainclude transmission line couplers TC₁ through TC_(a) which are coupledto ports P₁ through P_(a) and load resistors R₁ through R_(a). In anexemplary embodiment, the load resistors R₁ through R_(a) representsurface mount resistors. The transmission line coupling blocks 202.1through 202.a operate in a substantially similar manner; therefore, onlythe transmission line coupling block 202.1 is to be discussed in furtherdetail below.

The transmission line coupler TC₁ represents a pair of coupledtransmission lines. The pair of coupled transmission lines representbidirectional transmission lines to route various signals between theport P₁ and one or more of the transmission line coupling blocks 202.1through 202.9. The pair of coupled transmission lines can be implementedusing planar waveguides, such as stripline or microstrip to provide someexamples. In an exemplary embodiment, the dimensions for the pair ofcoupled transmission lines are fractionally related to a wavelength (λ),such as

$\frac{\lambda}{4}$

to provide an example, of signals routed by the transmission linecoupling block 202.1. In some situations, the pair of coupledtransmission lines of each of the transmission line couplers TC₁ throughTC_(a) can have different dimensions. However, it is preferred that thepair of coupled transmission lines of each of the transmission linecouplers TC₁ through TC_(a) have substantially similar dimensions suchthat network parameters, such as admittance parameters (y-parameters),scattering parameters (S-parameters), and/or scattering transferparameters (T-parameters) to provide some examples, for each of thetransmission line coupling blocks 202.1 through 202.a are substantiallysimilar to each other.

As illustrated in FIG. 2, a first coupled transmission line TL₁ fromamong the coupled transmission lines connects the port P₁ and thetransmission line coupling blocks 202.2 through 202.a. The port P₁ canbe connected to a mechanical probe, such as the one or more mechanicalprobes mentioned above, to route signals to and/or from a semiconductorwafer, such as the semiconductor wafer 106 to provide an example, orcommunicatively connected to a source instrument, such as the one ormore source instruments of the semiconductor wafer tester 108 to providean example.

A first terminal of a second coupled transmission line TL₂ from amongthe coupled transmission lines is connected to the load resistor R₁ anda second terminal of the second coupled transmission line TL₂ is notterminated. In an exemplary embodiment, the load resistor R₁ isselectively chosen, approximately 25Ω to provide an example, to match animpedance present on the port P₁ to an internal impedance of thetransmission line coupling circuit 200 at node 204. For example, theload resistor R₁ can assume a value of approximately 25Ω to match theinternal impedance of the transmission line coupling circuit 200 betweenapproximately 5Ω and approximately 6Ω when nine transmission linecoupling blocks 202.1 through 202.9 are present within the transmissionline coupling circuit 200 and ports P₁ through P₉ are terminated with animpedance of approximately 50Ω. In the exemplary embodiment illustratedin FIG. 2, the load resistor R₁ is further connected to ground. However,in another exemplary embodiment, the load resistor R₁ is not terminatedto ground. This other exemplary embodiment can be particular useful whenthe signals being routed by the transmission line coupler are highenough in frequency that the inductive reactance of the signal pathcreates a notable impedance relative to load resistor R₁. In this otherexemplary embodiment, the direct termination of the load resistor R₁ toground can be replaced with a capacitive connection to ground. In afurther exemplary embodiment, the load resistor R₁ represents a surfacemount resistor that is attached, typically by soldering, to one or moresurface mounting pads. In this further embodiment, the pad geometries ofthe one or more surface mounting pads can be adjusted or “tuned” suchthat their shunt capacitance to ground resonates with the sum of variousseries inductance values, namely, 1) a signal path to the load resistorR₁, 2) a series inductance of the surface mount resistor itself, and 3)a ground return path. In this manner, the inductive parasitics of thesignal path are cancelled out and the load resistor R1 electricallybehaves as the desired, real resistance value necessary for propermatching.

Exemplary Mechanical Layout of the Transmission Line Coupler

FIG. 3A illustrates a mechanical layout of the transmission line coupleraccording to an exemplary embodiment of the present disclosure. Asillustrated in FIG. 3, a transmission line coupling circuit 300 includestransmission line coupling blocks 302.1 through 302.b formed onto aflexible substrate 304 to form a flexible circuit. In an exemplaryembodiment, the transmission line coupling circuit 300 includestransmission line coupling blocks 302.1 through 302.9 as illustrated inFIG. 3B. The transmission line coupling circuit 300 can represent anexemplary embodiment of the transmission line coupling circuit 200. Assuch, the transmission line coupling blocks 302.1 through 302.b canrepresent an exemplary embodiment of the transmission line couplingblocks 202.1 through 202.a.

The flexible substrate 304 forms a foundation for the transmission linecoupling circuit 300. The flexible substrate 304 can be implementedusing polyimide, polyether ether ketone (PEEK) or transparent conductivepolyester film. As illustrated in FIG. 3A, the transmission linecoupling circuit 300 can be implemented as a double-sided flex circuithaving two conductive layers on the flexible substrate 304. However,those skilled in the relevant art(s) will recognize that thetransmission line coupling circuit 300 can be implemented as asingle-sided flex circuit having a single conductive layer on theflexible substrate 304 to form the transmission line coupling circuit300 and/or a multilayer flex circuit having three or more conductivelayers on and/or within the flexible substrate 304 to form thetransmission line coupling circuit 300. The flexible substrate 304 canbe implemented in a shape of a regular closed geometric structure, suchas a regular polygon as illustrated in FIG. 3A to provide an example, anirregular closed structure, such as an irregular polygon to provide anexample, and/or any suitable combination of these closed structures thatwill be apparent to those skilled in the relevant art(s).

As illustrated in FIG. 3A, the transmission line coupling blocks 302.1through 302.b are formed onto the flexible substrate 304 in a circularmanner around a central point 306 of the flexible substrate 304. Forexample, the transmission line coupling block 302.1 extends radiallyfrom the central point 306 in a first radial direction and thetransmission line coupling block 302.2, adjacent to the transmissionline coupling block 302.1 in the circular manner, extends radially fromthe central point 306 in a second radial direction. The transmissionline coupling blocks 302.1 through 302.b are formed using one or moreconductive materials patterned onto one or more conductive layers of theflexible substrate 304. In an exemplary embodiment, each of thetransmission line coupling blocks 302.1 through 302.b are formed in asubstantially similar symmetrical manner around the central point 306.The one or more conductive materials can include aluminum (Al), Copper(Cu), Silver (Ag), Gold (Au), Tin (Sn), or Nickel (Ni) to provide someexamples, and/or combinations of these materials. In another exemplaryembodiment, the transmission line coupling blocks 302.1 through 302.bare formed using thin film deposition of the one or more conductivematerials. In another exemplary embodiment, the transmission linecoupling blocks 302.1 through 302.b are formed using a conductive foilmaterial of the one or more conductive materials.

FIG. 4 further illustrates the mechanical layout of the transmissionline coupler according to an exemplary embodiment of the presentdisclosure. As discussed above, the transmission line coupling circuit300 can be implemented as a double-sided flex circuit having twoconductive layers on the flexible substrate 304. As illustrated in FIG.4, the transmission line coupler can be formed on a first conductivelayer 400 of the flexible substrate 304, also referred to a top side ofthe flexible substrate 304, and a second conductive layer of theflexible substrate 304, also referred to a bottom side of the of theflexible substrate 304. It should be noted that the configuration andarrangement of the transmission line coupling blocks 302.1 through 302.bas illustrated in FIG. 4 is for illustrative purposes only. Thoseskilled in the relevant art(s) will recognize that other configurationsand arrangements of the transmission line coupling blocks 302.1 through302.b are possible without departing from the spirit and scope of thedisclosure.

FIG. 5 illustrates a mechanical layout of a transmission line couplingblock of the transmission line coupler according to an exemplaryembodiment of the present disclosure. A transmission line coupling block500 is formed onto a first conductive layer 502 of the flexiblesubstrate 304 and a second conductive layer 504 of the flexiblesubstrate 304. The transmission line coupling block 500 can represent anexemplary embodiment of one or more of the transmission line couplingblocks 302.1 through 302.b. As illustrated in FIG. 5, the firstconductive layer 502 includes a first conductive trace 506 extendingfrom a port P of the transmission line coupling block 500, such as oneor more of ports P₁ through P_(a) in FIG. 2 to provide an example, to afirst coupled transmission line TL₁ of a transmission line coupler, suchas one or more of the transmission line couplers TC₁ through TC_(a) inFIG. 2 to provide an example. As additionally illustrated in FIG. 5, thefirst conductive layer 502 includes a second conductive trace 508between a load resistor R, such as one of the load resistors R₁ throughR_(a) to provide an example, and a via 510. This via 510 electricallyconnects the second conductive trace 508 to a second coupledtransmission line TL₂ of the transmission line coupler on the secondconductive layer 504. In some situations, trace widths of the firstconductive trace 506 and of the second conductive trace 508 can vary,for example, to achieve a desired characteristic impedance. For example,as illustrated in FIG. 5, a first trace width of a first portion of thesecond conductive trace 508 is less than a second trace width of asecond portion of the second conductive trace 508. Moreover, the tracewidths of the first coupled transmission line TL₁ and/or the secondcoupled transmission line TL₂ can also be changed to achieve a desiredcoupling factor and/or impedance match as will be recognized by thoseskilled in the relevant art(s) without departing from the spirit andscope of the present disclosure.

FIG. 6 illustrates a mechanical layout of a transmission line coupler ofthe transmission line coupling block according to an exemplaryembodiment of the present disclosure. A transmission line coupler 600 isformed onto the first conductive layer 502 of the flexible substrate 304and the second conductive layer 504 of the flexible substrate 304. Thetransmission line coupler 600 can represent an exemplary embodiment ofone or more of the transmission line couplers TC₁ through TC_(a) in FIG.2.

As illustrated in FIG. 6, a first end of a first coupled transmissionline TL₁ of the transmission line coupler 600 is electrically connectedto the central point 306 and a second end of the first coupledtransmission line TL₁ is electrically connected to the first conductivetrace 506 on the first conductive layer 502. A portion of the firstconductive trace 506 is illustrated in FIG. 6.

A first end of a second coupled transmission line TL₂ of thetransmission line coupler 600 is unterminated and not electricallyconnected to the central point 306. A second end of the second coupledtransmission line TL₂ is connected to the via 510 on the secondconductive layer 504. The via 510 is further electrically connected tothe second conductive trace 508 on the first conductive layer 502. Aportion of the second conductive trace 508 is illustrated in FIG. 6.

As shown in FIG. 6, the first coupled transmission line TL₁ and thesecond coupled transmission line TL₂ are disposed on opposing sides ofthe flexible substrate 304, and at least partially overlay one anotherto effect spatial coupling of electrical signals between the firstcoupled transmission line TL₁ and the second coupled transmission lineTL₂.

CONCLUSION

The Detailed Description referred to accompanying figures to illustrateexemplary embodiments consistent with the disclosure. References in thedisclosure to “an exemplary embodiment” indicates that the exemplaryembodiment described include a particular feature, structure, orcharacteristic, but every exemplary embodiment can not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same exemplaryembodiment. Further, any feature, structure, or characteristic describedin connection with an exemplary embodiment can be included,independently or in any combination, with features, structures, orcharacteristics of other exemplary embodiments whether or not explicitlydescribed.

The exemplary embodiments described within the disclosure have beenprovided for illustrative purposes, and are not intend to be limiting.Other exemplary embodiments are possible, and modifications can be madeto the exemplary embodiments while remaining within the spirit and scopeof the disclosure. The disclosure has been described with the aid offunctional building blocks illustrating the implementation of specifiedfunctions and relationships thereof. The boundaries of these functionalbuilding blocks have been arbitrarily defined herein for the convenienceof the description. Alternate boundaries can be defined so long as thespecified functions and relationships thereof are appropriatelyperformed.

The Detailed Description of the exemplary embodiments fully revealed thegeneral nature of the disclosure that others can, by applying knowledgeof those skilled in relevant art(s), readily modify and/or adapt forvarious applications such exemplary embodiments, without undueexperimentation, without departing from the spirit and scope of thedisclosure. Therefore, such adaptations and modifications are intendedto be within the meaning and plurality of equivalents of the exemplaryembodiments based on the teaching and guidance presented herein. It isto be understood that the phraseology or terminology herein is for thepurpose of description and not of limitation, such that the terminologyor phraseology of the present specification is to be interpreted bythose skilled in relevant art(s) in light of the teachings herein.

What is claimed is:
 1. A transmission line coupling circuit, comprising:a plurality of transmission line coupling blocks, the plurality oftransmission line coupling blocks comprising: a plurality oftransmission line couplers having a plurality of first coupledtransmission lines and a plurality of second coupled transmission lines;and a flexible substrate, wherein the plurality of first coupledtransmission lines is connected to a plurality of ports, wherein theplurality of second coupled transmission lines is connected to aplurality of load resistors, and wherein the plurality of transmissionline coupling blocks is formed onto the flexible substrate in a circularmanner around a central point of the flexible substrate.
 2. Thetransmission line coupling circuit of claim 1, wherein the flexiblesubstrate includes a top side and a bottom side, wherein the pluralityof first coupled transmission lines is implemented on the top side ofthe flexible substrate, and wherein the plurality of second coupledtransmission lines is implemented on the bottom side of the flexiblesubstrate.
 3. The transmission line coupling circuit of claim 2, whereinthe top side further comprises: a plurality of first conductive tracesconnecting the plurality of ports and the plurality of first coupledtransmission lines, the plurality of first coupled transmission linesconnected to the central point, and a plurality of second conductivetraces connecting the plurality of load resistors and a plurality ofvias, and wherein the bottom side comprises: the plurality of secondcoupled transmission lines connected to the plurality of vias.
 4. Thetransmission line coupling circuit of claim 1, wherein the plurality offirst coupled transmission lines and the plurality of second coupledtransmission lines each comprises: conductive foil material.
 5. Thetransmission line coupling circuit of claim 1, wherein the plurality ofload resistors comprises: a plurality of surface mount resistors.
 6. Thetransmission line coupling circuit of claim 1, wherein the flexiblesubstrate comprises: polyimide.
 7. The transmission line couplingcircuit of claim 1, wherein the plurality of transmission line couplersis configured to match impedances present on the plurality of ports toan internal impedance of the transmission line coupling circuit.
 8. Aprobe card for testing a plurality of integrated circuits formed onto asemiconductor substrate forming a semiconductor wafer, the probe cardcomprising: a plurality of mechanical probes configured to contact aplurality of contact pads on the semiconductor wafer; a plurality oftransmission line coupling circuits connected to the plurality ofmechanical probes, the plurality of transmission line coupling circuitsconfigured to route a plurality of testing signals between thesemiconductor wafer and a semiconductor wafer tester, and the pluralityof transmission line coupling circuits formed onto a flexible substrate.9. The probe card of claim 8, wherein a transmission line couplingcircuit from among the plurality of transmission line coupling circuitscomprises: a plurality of transmission line coupling blocks, theplurality of transmission line coupling blocks comprising: a pluralityof transmission line couplers having a plurality of first coupledtransmission lines and a plurality of second coupled transmission lines,the plurality of first coupled transmission lines connected to aplurality of ports, the plurality of second coupled transmission linesconnected to a plurality of load resistors, wherein the plurality oftransmission line coupling blocks is formed onto the flexible substratein a circular manner around a central point of the flexible substrate.10. The probe card of claim 9, wherein the flexible substrate includes atop side and a bottom side, wherein the plurality of first coupledtransmission lines is implemented on the top side of the flexiblesubstrate, and wherein the plurality of second coupled transmissionlines is implemented on the bottom side of the flexible substrate. 11.The probe card of claim 10, wherein the top side comprises: a pluralityof first conductive traces connecting the plurality of ports and theplurality of first coupled transmission lines, the plurality of firstcoupled transmission lines connected to the central point, and aplurality of second conductive traces connecting the plurality of loadresistors and a plurality of vias, and wherein the bottom sidecomprises: the plurality of second coupled transmission lines connectedto the plurality of vias.
 12. The probe card of claim 9, wherein theplurality of first coupled transmission lines and the plurality ofsecond coupled transmission lines each comprises: thin film deposition.13. The probe card of claim 9, wherein the plurality of load resistorscomprises: a plurality of surface mount resistors.
 14. The probe card ofclaim 8, wherein the flexible substrate comprises: polyimide.
 15. Theprobe card of claim 9, wherein the plurality of transmission linecouplers is configured to match impedances present on the plurality ofports to an internal impedance of the transmission line couplingcircuit.
 16. A transmission line coupling block of a transmission linecoupling circuit, the transmission line coupling block comprising: atransmission line coupler having a first coupled transmission line and asecond coupled transmission line; and a flexible substrate, wherein thefirst coupled transmission line is connected to a port, wherein thesecond coupled transmission line is connected to a load resistor, andwherein the transmission line coupling block is from among a pluralityof transmission line coupling blocks, the plurality of transmission linecoupling blocks formed onto the flexible substrate in a circular manneraround a central point of the flexible substrate.
 17. The transmissionline coupling block of claim 16, wherein the flexible substrate includesa top side and a bottom side, wherein the first coupled transmissionline is implemented on the top side of the flexible substrate, andwherein the second coupled transmission line is implemented on thebottom side of the flexible substrate.
 18. The transmission linecoupling block of claim 17, wherein the top side comprises: a firstconductive trace connecting the port and the first coupled transmissionline, and a second conductive trace connecting the load resistor and avia.
 19. The transmission line coupling block of claim 16, wherein theflexible substrate comprises: polyimide.
 20. The transmission linecoupling block of claim 16, wherein the first coupled transmission lineis connected to the central point, and wherein the second coupledtransmission line is not connected to the central point.